Schematic

Measured and Calculated Currents
Advanced Digital Motor Controller User Manual 31
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FIGURE 1-3. Current flow during operation
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FIGURE 1-4. Instant and average current waveforms
The relation between Battery Current and Motor current is given in the formula below:
Motor Current = Battery Current / PWM Ratio
Example: If the controller reports 10A of battery current while at 10% PWM, the current in
the motor is 10 / 0.1 = 100A.
Measured and Calculated Currents
All Roboteq Brushed DC motor controllers, have current sensors for measuring the bat-
tery current and estimate the motor current. At 20% PWM and above, the motor current
is computed using the formula above. Below 20%, and approaching 0%, this method
cause unstable and imprecise readings. At these levels, formula used is
Motor Current = Battery Current / 0.20
This approximation creates a more stable value but one that is increasingly inaccurate as
the PWM approaches 0%. This approximation produces usable value nevertheless.
Roboteq’s Brushless motor controllers use sensors on the motor outputs or/and on the
battery ground terminal. Controllers using sensors on the battery terminal outputs suffer
the same limitation at low PWM as discussed above.